Stopping on a Mountain Descent with a Hot Brake Warning
You are driving a category D bus down a long mountain descent, about 6 km of continuous 7% gradient, with 25 passengers. The road is dry and the speed limit is 70 km/h. About 3 km into the descent you notice the service brake pedal feels longer and the bus is not slowing as sharply as before; a brake-temperature warning lamp has come on. There is a lay-by 150 m ahead on the right, wide enough for the bus, with a slight uphill entry. Beyond the lay-by the descent continues for another 3 km. There is a sharp right-hand bend 400 m ahead. Traffic behind you is light, with one car about 80 m back. Your parking brake is working, and you have a wheel chock in the luggage hold.
1. What is your immediate plan, and why is the lay-by the right target rather than continuing to the end of the descent?
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The warning lamp plus a long pedal means the brakes are overheating - continuing risks fade and then total loss of service braking on a 7% gradient with 25 passengers, which is one of the most serious situations a bus driver can face. The lay-by at 150 m is the correct target: it is close, it is wide enough for the bus, and its slight uphill entry helps slow you. The plan is to reduce speed using engine braking (a lower gear) rather than more pedal, signal early to warn the car 80 m back, and stop in the lay-by. Continuing the remaining 3 km, especially through a sharp bend at 400 m, is the wrong judgement because brake fade worsens with heat and the bend demands braking you may not have.
2. How do you secure the bus in the lay-by, and what do you check before resuming?
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Stop fully in the lay-by, apply the parking brake, select a low gear or park, switch on hazard warning lights, and place the wheel chock behind a wheel facing downhill so the bus cannot roll. Let the brakes cool - do not pour water on hot drums or discs. Before resuming, check that the warning lamp has gone out and the pedal feels normal, and confirm no brake fluid loss or burning smell. If the pedal is still long, the correct decision is not to continue but to call for assistance. Resuming should be done in a low gear, using engine braking as the primary speed control on the remaining descent, with the service brake used in short applications rather than continuously.
3. What do you tell the passengers, and how does the presence of the car 80 m behind affect your signalling?
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Passengers should be told briefly and calmly that the bus is stopping for a brake check, that they should remain seated, and that no one should stand in the aisle. Panic is a bigger risk than the stop itself. The car 80 m behind is close at descent speeds - at 70 km/h it is only about 4 seconds back - so hazard lights and an early, steady signal are needed before you slow, and you should begin slowing gradually so the car can react. The judgement tested is that communication (to passengers and to following traffic) is part of the emergency response, not an afterthought.